The invention relates generally to head restraint support tubes for allowing sliding motion between two components and more specifically to tubular guide members for use in guiding vehicle head restraints during vertical adjustment.
Head restraint support tubes of the type described herein are typically used in vehicles as a structural member that allows the head restraint to be attached to the seat back. The head restraint typically has one or more vertical posts that allow the head restraint to move up or down while maintaining alignment and still being firmly held in the seat. This is accomplished via a plastic guide inserted into the head restraint support tube that guides the vertical posts.
In many previous head restraint support tubes, the head restraint support tube inside diameter is too large, allowing the plastic guides to rattle within the head restraint support tube during vehicle operation. Due to the proximity of the head restraint support tube to the driver""s head, the rattling can be noticeable. It is therefore desirable to provide a tightly toleranced fit between the plastic guide and the head restraint support tube to prevent rattling. However, if the fit is too tight, assembly of the plastic guide will be difficult causing high effort to raise and lower the head restraint assembly. It is desirable that head restraint adjustment be simple and easy, encouraging users to properly adjust the head restraint to prevent potential injuries in a collision. A properly sized head restraint support tube will contain the plastic guide so as to restrain the vertical post sufficiently to prevent rattling while still allowing easy adjustment.
While inserting the plastic guide into the head restraint support tube, it is possible for the plastic guide to contact the inner circular edges of the head restraint support tube. In these situations, it is possible for the head restraint support tube to scratch or score the plastic guide during assembly. Therefore, in some applications it is important to reduce the likelihood of this type of damage when using head restraint support tubes of the type described herein.
The present invention provides for a tightly toleranced fit between the head restraint support tube and the vertical post by providing a tube having a portion with a reduced diameter to firmly restrain the plastic guide and vertical post to prevent rattling. To further reduce manufacturing costs, the invention uses a flat sheet having first and second sides shaped to allow for an interlocking arrangement. The sheet is formed into a tubular shape having a first and second end wherein the first and second sides interlock. The inside diameter of a portion of the tube adjacent to one end may be smaller than the remainder of the tube. In addition to reducing the diameter of a portion of the tube, the invention may reduce the potential for rattling by forming lances at either or both ends of the tube. The lances restrain the plastic guide without substantially increasing the force required to adjust the head restraint.
Another feature of the invention is the use of rounded or filleted ends to reduce the likelihood of damage to the plastic guide as it is assembled (inserted) into the head restraint support tube.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.